Fixes#85447
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This PR resolves a crash in `ActOnUninitializedDecl` due to an oversight
in updating the `isInvalidDecl` state before invocation. The crash
occurs due to a missing invocation of `setInvalidDecl()` for an invalid
`Anon` declaration. To address this issue, the `setInvalidDecl()` method
is now properly invoked to mark the `Anon` declaration as invalid before
running `ActOnUninitializedDecl()`.